There are numerous warnings that, in time, AI will cause human extinction. A popular one is that robots will take over the world and eliminate all human life. Although that seems highly unlikely, the scenario that seems plausible is that autonomous weapons could eliminate humanity. If nuclear bombs are given their own decision making, and more and more military weapons are heading in that direction, then AI causing humanity to cease is not as farfetched as so many people believe.
Just Logical
Firing nuclear weapons is a decision that should never be made by people when their emotions are at their highest. As a result, removing the human element might seem appropriate in the future. However, no matter how many war games are simulated on computers, the end result of a decision made by a machine is why people are very concerned about the potential for AI to be catastrophic for humanity. See
autonomous weapon.